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"They found the capacitor start system was blown up all over the electrical cabinet. They installed a new start system, and then recommended me to get a infinity thermostat. I told them sure. After installing this stat, the unit worked PERFECT for about 3 days."

Did you not read the part that it did indeed work perfect for 3 days. Then the board fried and the whole outdoor unit was dead no flashing lights and no low voltage control. After the new board was installed he never let it work corrctly instead just for the heck of it with his fingures pressed in the contactors. The new board is working because it detected a bad compressor and flashed a code.

Dear Mr Supervisor

as I am sure you know ...when 24 v is applied to the contactor the electromagnetic coil pulls in the contactor from the oppisite side that the 18 yr old puke pushed in....

it makes no difference weather you push it in or it pulls in , the contacts are made and power is applied to the unit and if you saw smoke , it didnt come out of the compressor without an explosion of smoke and referigerant under pressure

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If the compressor failed it did so because you tried starting it while it was humming and not starting several times...not because someone pushed in a contactor

Ok, enough bashing already. I know we all love to hear these homeowners moan and groan but he may just have a point. Those of us who are electrical guru's look at the diagram and give us your input on weather or not it will fry the compressor if "BOTH" contactors were to be energized. I think it may if the internal overload was welded closed inside the compressor. It looks to be designed for either one or the other, not both at the same time.

You need multiple drier changes and acid tests after the new compressor is installed. Get ahold of Carrier if the dealer doesn't play ball correct.

BTW, I'd trust an electrician to wire my house, but not my AC.

Replace your contactors regularly. I've seen one set stick and the other pull in on a Waterfurnace and it destroyed the compressor.

I've only worked on a couple of those units before I left the dealer I worked for. It's not a 2 speed compressor, but a dual capacity. Compressor spins one way for low and the other for high. During high the crank picks up a second piston with a special cluth.

That's not the greatest wiring diagram I've ever seen...in fact it can be a bit confusing at first glance. If you study it, there appears to be a direct short between L1 and L2 at the contactors. I'm assuming it was drawn as it was to represent a wiring harness, but that should be called out, IMO. A ladder diagram would be much better with a unit that has a bit more complexity involved like here.

Here's a pic of the 18 SEER Infinity from Carrier's website:

Looks like a recip is in there to me, and the tech data on the site would appear to affirm this. If that's the case it is not a reversing compressor...what would be the point? Why reverse a recip when you can just run it at half speed in the same direction, thereby accomplishing the sought for reduction in capacity?

NOTE: Reconsidering I could be wrong...have heard of a recip that does reverse direction and has the clutch mechanism referred to in the above post. I think Bristol makes it?

The compressor motor is easily reversed and allowed to operate at peak efficiency by using the start winding of the two-piston operation as the run winding, and the run winding as the start winding, the company explains. One additional relay in the run-winding circuit makes this happen.

In reversing motor direction, Bristol employs either a two-minute-delay in the relay to allow system equalization, or a hard-start kit to allow the motor to reverse against load. Capacity choice is controlled by a standard mechanical or electronic two-stage thermostat

So it would appear manually engaging both contactors simultaeously would indeed smoke the compressor.

The young tech made an expensive mistake. I personally avoid manually pushing in contactors whenever possible (and I'd NEVER do it with my FINGERS!!) If a proper cleanup is done the system should be fine. I can't imagine every time an R410A system with POE in it blows a compressor it automatically indicates a complete change-out of everything. Same procedures for cleaning up an R22 burnout should go for R410A, IMO.

To the OP, ya the tech screwed things. Get that comp replaced. Ensure they do a proper cleaning of the system...i.e., multiple trips to check and replace driers as necessary until system is properly cleaned.

If it was me, I'd roll back the foreskin and jump on the new unit bandwagon, but I can really be a d***head when I want to be one!

For future reference, secure the unit once it starts dimming lights. Don't let it keep dimming the lights in hopes of a little cooling.

push both at the same time will smoke the compressor even if only few seconds. k-1 is high speed and k-2 is low speed
i added k1 and 2 just for example not on diagram. one drops out and the other pulls in and is controled by the board. pushing them in at the same time brings on both speeds at the same time or at least tries to anyway
tech screwed up. i am sure the contractor will not have a problem standing behind the unit and we do all make mistakes

I havn't worked on an Infinity system yet, but I have a book on the Bristol TS compressor used in them.

Pushing in both contactors at the same time looks like it would have about the same effect on the compressor as wiring start and run together with no capacitor on a normal compressor. Not instantly disasterous 100% of the time, but certainly not good at all for the motor windings inside.
It looks like pushing both contactors in could definatly do a number on the external wiring to the compressor though.

I would say it was a very bad thing for him to push both contactors in at once.

Only one comment, shouldn't techs get trained on these systems before they come on site to perform any work! Companies like Trane, Carrier, York, Lennox, have training classes. I would think that any company that says they service these units spend little $$ to get their techs trained! It perturbs me that from what I am hearing training on certain equipement is not part of everyones backround!

Originally posted by kevinmac Only one comment, shouldn't techs get trained on these systems before they come on site to perform any work! Companies like Trane, Carrier, York, Lennox, have training classes. I would think that any company that says they service these units spend little $$ to get their techs trained! It perturbs me that from what I am hearing training on certain equipement is not part of everyones backround!

i cant speek for anyone else here. anytime a new product come out from lenos or trane i set up for the guys to go to the class on it. it is thier option to show since it is normaly at night. most companies do the same. if the guys dont show there is not much can be done about that. for the guys that cant make the siminar or class the next day or with in a couple days i go over what was done at the class so they keep up. not trying to make excuses but some guys dont like to go or learn anything new. what a lot of guys dont understand is if we want to get better and learn more then we may have to put in a little of our own time.
in most cases the guys are not getting paid to be there and feel they shouldnt have to go. this is why i will go over it with some of them. we also have a class once every two weeks at the shop for about an hour or so going over service points and install points. just trying to keep it right